The UN atomic agency says Iran has complied with a key commitment of a nuclear agreement with major world powers by removing sensitive equipment from an underground site.

In a January 16 statement, Yukiya Amano head of the International Atomic Energy Agency (IAEA) said that Tehran had met a deadline and taken "excess centrifuges and infrastructure" from its Fordow facility.

The statement said that Amano confirms that on January 15 "the Agency verified that Iran has taken these actions related to Fordow" within the timeline stipulated in the nuclear deal.

The 2015 deal stated that no more enrichment would take place at the Fordow site near the holy city of Qom for 15 years, but that Iran could keep just over 1,000 centrifuges there for research and other non-enrichment purposes.

Under the nuclear agreement reached last year with the U.S. and other world powers, Iran has significantly limited its sensitive nuclear activities in exchange for sanctions relief.